The construction of a building requires the coordination of a variety of specialized work. The ground is excavated and the foundation is poured. The outer walls and roof are erected, and the framing of the interior walls are roughed in. The plumbing, electrical wiring, heating and ventilation, and other concealed or built in components and features are installed. Industrial buildings often have large pieces of equipment that need to be set in place and hooked up to the electrical, water and pneumatic systems in the building. Residential and commercial buildings require additional work such as installing insulation, drywall, cabinets, finished floor coverings and woodwork, as well as painting are frequently done before the permanent electrical system is operating for the building. During construction, electric power is typically provided in the form of a temporary 120-volt, 200-amp service to run tools and equipment and provide necessary lighting to the interior of the building. Temporary pedestals are connected to this service and installed at desired locations around the building. The pedestals are frequently 200 feet apart and are equipped with a 20-amp breaker. Temporary lighting is run from the pedestals to provide a safely lit and productive environment for the workers during the construction of the interior of the building.
Temporary construction lighting stringers typically take the form of relatively long, continuous, electric cords with a number of integrally attached light fixtures that are evenly spaced along the length of the stringer. The stringers are pre-assembled with each fixture secured to the cord. The stringers join the lights in series and are typically sold in 50 to 100 feet long strands with a light fixture every 10 feet. Many stringers have a conventional three-prong male plug at one end for plugging into an outlet of one of the temporary pedestals. The stringers need to provide enough light for the larger areas of a building, and to reach the more remote locations in the building relative to the pedestals. Stringers plugged into adjacent pedestals should be able to light the area between those pedestals. The routing of a conventional stringer through a building is shown in FIG. 1. Stringers are typically not removed until toward the end of the construction of the interior of the building.
A problem with temporary construction lighting stringers is that they are used once and discarded. Because different work is done by different contractors at different times throughout the construction of a building, the interior walls, electric wiring, plumbing, ductwork, and other components are installed around and intertwined with the lighting stringers. The relatively large lighting fixtures frequently do not fit through the small openings between the wall framing and other components through which the electric cord of the stringer extends. The cord also becomes intertwined with the permanent wiring for the electrical, telephone, fire and security systems for the building. Removing the stringers is often rendered impractical without cutting or otherwise destroying the cord. Yet, when the cord is cut, the entire stringer is rendered unusable. To perform work quickly, lighting contractors and their workers typically do not have or take the time to untangle the cord or detach and reattach obstructed fixtures in order to remove a stringer. The lighting contractor will also not want to interfere with the wiring of the other contractors in order to remove a stinger. The stringer is simply cut and discarded. While splicing the stringer back together may be permitted under Article 527.4(G), OSHA inspectors typically frown on temporary light stringers with numerous splices because of the increased safety risk the splices pose. Yet, expensive temporary stringers that have been used on more than one job site often have many splice points, which increases the risk of a hazardous situation. As a result, new stringers are needed for each construction site, and the waist is added in to the construction costs. Unfortunately, workers and foremen can be unduly frugal with installing temporary lighting in order to keep costs to a minimum. In some instances, the necessary stringers for appropriate lighting may only be installed after an accident occurs or a safety inspector requires additional lighting.
Another problem with conventional construction lighting stringers is that they come in a unitary strand having a length 50 to 100 feet. Some stringers are initially hung to provide general lighting for the relatively open interior area of the building after the roof and outer walls are erected. These stringers are often too far from a specific area where detailed work needs to be done or become obscured by the interior walls and other components in the building. Yet, the stringers can become stuck or intertwined with other components as the construction of the interior progresses. Instead of simply moving or rerouting an existing stringer, additional stringers need to be added and routed to specific areas throughout the construction process as interior lighting needs change. The need to reroute stringers can be particularly important when the interior rooms take form and lighting is needed in each room. The unitary strand or lights must be routed from one room to another, and into and out of each room as in FIG. 1. Even a long strand will quickly be used up. The stringers cannot properly light the areas near the pedestal and the more remote rooms relative to the pedestal. Although additional stringers can be plugged directly into the pedestal or into a receptacle at the end of an existing stringer, the additional stringers can overload the 20 amp breaker in the pedestal, increase construction costs and be a nuisance or safety hazard to the workers. The additional stringers can be particularly troublesome when they are routed through doorways, walkways or openings used by the workers or overload the electrical capacity of a particular pedestal.
A further problem with construction lighting stringers is that they must be reliable and easy to install and remove. The stringers must be able to withstand considerable physical and environmental abuse. The electric connections between the electric cords and light fixtures need to be firm so that they are not jarred lose during rugged use. Yet, the need for durability and reliability conflicts with the ease with which the stringers and fixtures are installed and removed. Although some construction stringers have been developed to help remove the light fixtures, the fixtures are in practice too difficult to remove and properly reinstall in a safe and reliable manner. An example of such a stringer is shown in U.S. Pat. No. 6,425,682 and D439,697, the disclosures of which is incorporated by reference. These stringers are preassembled by the manufacturer with light fixtures attached to the cord about every ten feet. The fixtures have clamps with electrical contacts that pierce the two spaced electrical cords to form the electrical contact with the wires and necessary firm securement to the cord. These clamps must be opened to remove the fixture from the cord, which exposes the existing holes in the cord and creates a potential for a short circuit or safety risk if the holes are not properly covered due to an oversight due to a busy construction setting. If the fixture is reattached at a different location on the cord, then the cord has to be cut between the two wires so that the wires can be spread apart for reattachment to the spaced clamps of the fixture. Should the knife slip, one of the electrical wires can be severed or the worker can be injured. Reattachment is often unreliable because one or both of the contacts of the clamp do not pierce and firmly engage their respective wire. As a result, workers typically view removing and reattaching the light fixtures as unproductive and simply add another stringer. As noted above, adding new stringers in lieu of rerouting an existing stringer increases construction costs and can overload the pedestal breaker. The additional stringers will also need to be cut and discarded at the end of the construction project if they become stuck or intertwined and difficult to remove.
A still further problem with construction lighting stringers is that they must comply with specific construction code requirements such as the OSHA standard 29 C.F.R. 1926.405(a)(2) for Temporary Wiring, and the National Electric Code Articles 305 and 527 for Temporary Wiring and Temporary Installations, respectively. These codes require temporary lighting assembles to be approved for the conditions in which they are being applied (Article 527.2 (B), have feeders and branch circuits with hard usage type cords (Article 527.4 (C), and meet specific slicing requirements. (Article 527.4 (G)). The codes also prohibit temporary lighting from have receptacles, particularly if the temporary lighting system has an ungrounded conductor. (Article 527.4 (D)). The reason for this code requirement is believed to be to prevent the temporary lighting from providing standard configuration receptacles that would allow workers to plug in an electric tool, battery charger, radio, or the like, which could create a safety concern.
Conventional trouble lights are not appropriate for construction settings because they do not comply with OSHA and National Electric Code requirements. Examples of conventional trouble lights are provided in U.S. Pat. Nos. 6,425,682, 5,257,172 and 5,154,511, the disclosures of which are incorporated by reference. Trouble lights are not typically designed for hard use as required by Article 527.4(C). The cord is not physically tough enough, so that the cord and its conductive wires could be damaged or cut should the cord be struck by a hammer or passed over a sharp edge. The trouble lights that provide a receptacle have a standard outlet configuration in violation of Article 527.4(D). The standard outlet configuration allows workers to plug in a tool or piece of equipment with a standard prong configuration into the receptacle of the trouble light, which creates a potential safety hazard. The wiring or circuitry of the trouble light could overheat or short circuit, and cause a blackout or fire. In addition, trouble lights do not provide the necessary lighting capacity needed for a construction setting. Trouble lights often have a lamp with a light bulb shield that limits the emission of light to about or less than 180 degrees. Trouble lights are also usually intended for 100 watt or less bulbs. For these and other reasons, trouble lights would not be appropriate or approved for temporary lighting applications under Article 527.2(B) for the vast majority if not all construction conditions, particularly if they were connected in series or in a multi-branch layout.
The present invention is intended to solve these and other problems.